Microsoft said they awarded such a large prize because Mr Forshaw's submission would help them "develop defences against entire classes of attack".

Mr Forshaw explained how he found the bug: "Over the past decade working in secure development and research, I have discovered many interesting security vulnerabilities with a heavy focus of complex logic bugs.

"I’m keenly interested in the intellectual puzzle of finding novel exploitation techniques and the creativity it requires ... To find my winning entry I studied the mitigations available today and after brainstorming I identified a few potential angles. Not all were viable but after some persistence I was finally successful."

Microsoft's bounty system reflects a wider monetisation of cyber hacking which has developed as governments and businesses become more aware of the issue.